Quick question about fuel pressure regulator vacuum hose

Hi Everyone

I'm new to the forum, and realitively new to BMW's.

Thanks already for all of your contributions! It has helped greatly in diagnosing and fixing a few issues I'm sifting through.

Here's a quick question for the experts.

Is there supposed to be fuel in the vacuum hose that runs from the fuel pressure regulator to the rear intake plate...(or pvc plate)? Mine does...This is raising a red flag with me. Your knowledge is appreciated!

The vehicle is a 94 530i touring, stock with an m60 motor. It's been fun to work on...so far.

Thanks again
AA

Here's a video of air bubbles making their way into the rear manifold plate. This is after the engine was turned off.



I've been having trouble with hard starts when the engine is warm, but sitting for 10+ minutes. I suspect this is the culprit, flooding the intake manifold.

No fuel in a vacuum hose. You have a ruptured diaphragm or similar in your system somewhere. This will definitely give you the poor warm start problem.

Thanks for confirming BMW FF!

I disconnected the vacuum hose and plugged the ends. Ran the engine up to op temp and shut it down for 15 min. Started right up! First time thats happened in a loooong time!

Never would have found that prob had I not installed that clear hose.

Looks like I have the task of replacing the FPR....right after coffee in the morning!

Clear hoses rule!
AA

^except they melt easily.

Hi, my problem appears to be very similar, where does the vacuum pipe from the FPR terminate? when the engine is off i can blow down the pipe easily with no apparent pressure build, resistance (back pressure) is this expected to be normal?

Yes - normal. It opens into the inlet manifold so that the diaphragm cam be exposed to manifold drpression.